Bio: Bio-engineer that worked for Oscorp in New Orleans that experimented on himself with hypnotic persuasion and "urban stealth".
Notes: The Ultimate version of this character is not an alternate identity of the regular Marvel character as the Ultimate universe is a distinct reality.
As proven in the "Ultimate Doom" miniseries, in the Ultimate universe, there also exists a Nathaniel Essex working for the Roxxon company. Therefore it is unknown what this Sinister's real name is.
See here for more information.
Nick Fury found that his DNA matches that of a "Nathaniel Essex".
#46 - 'The Tempest: Part 1' #47 - 'The Tempest: Part 2' #48 - 'The Tempest: Part 3' #49 - 'The Tempest: Part 4' #63 - 'Magnetic North: Part 3' #65 - 'Magnetic North: Part 5' #81 - 'Cliffhangers' #90 - 'Apocalypse: Part 1' #91 - 'Apocalypse: Part 2'